Use `execute_batch2` rather than `execute_batch` to fix performance regression for fixture loading

d8d6bd5 makes fixture loading to bulk statements by using
`execute_batch` for sqlite3 adapter. But `execute_batch` is slower and
it caused the performance regression for fixture loading.

In sqlite3 1.4.0, it have new batch method `execute_batch2`. I've
confirmed `execute_batch2` is extremely faster than `execute_batch`.
So I think it is worth to upgrade sqlite3 to 1.4.0 to use that method.

Before:

```
% ARCONN=sqlite3 bundle exec ruby -w -Itest test/cases/associations/eager_test.rb -n test_eager_loading_too_may_ids
Using sqlite3
Run options: -n test_eager_loading_too_may_ids --seed 35790

# Running:

.

Finished in 202.437406s, 0.0049 runs/s, 0.0049 assertions/s.
1 runs, 1 assertions, 0 failures, 0 errors, 0 skips
ARCONN=sqlite3 bundle exec ruby -w -Itest  -n test_eager_loading_too_may_ids  142.57s user 60.83s system 98% cpu 3:27.08 total
```

After:

```
% ARCONN=sqlite3 bundle exec ruby -w -Itest test/cases/associations/eager_test.rb -n test_eager_loading_too_may_ids
Using sqlite3
Run options: -n test_eager_loading_too_may_ids --seed 16649

# Running:

.

Finished in 8.471032s, 0.1180 runs/s, 0.1180 assertions/s.
1 runs, 1 assertions, 0 failures, 0 errors, 0 skips
ARCONN=sqlite3 bundle exec ruby -w -Itest  -n test_eager_loading_too_may_ids  10.71s user 1.36s system 95% cpu 12.672 total
```

Gemfile

@@ -118,7 +118,7 @@ platforms :ruby, :mswin, :mswin64, :mingw, :x64_mingw do
   gem "racc", ">=1.4.6", require: false
 
   # Active Record.
-  gem "sqlite3", "~> 1.3", ">= 1.3.6"
+  gem "sqlite3", "~> 1.4"
 
   group :db do
     gem "pg", ">= 0.18.0"

Gemfile.lock

@@ -278,6 +278,7 @@ GEM
     image_processing (1.7.1)
       mini_magick (~> 4.0)
       ruby-vips (>= 2.0.13, < 3)
+    jar-dependencies (0.4.0)
     jaro_winkler (1.5.2)
     jaro_winkler (1.5.2-java)
     jdbc-mysql (5.1.46)
@@ -468,9 +469,7 @@ GEM
       actionpack (>= 4.0)
       activesupport (>= 4.0)
       sprockets (>= 3.0.0)
-    sqlite3 (1.3.13)
-    sqlite3 (1.3.13-x64-mingw32)
-    sqlite3 (1.3.13-x86-mingw32)
+    sqlite3 (1.4.0)
     stackprof (0.2.12)
     sucker_punch (2.1.1)
       concurrent-ruby (~> 1.0)
@@ -582,7 +581,7 @@ DEPENDENCIES
   sidekiq
   sneakers
   sprockets-export
-  sqlite3 (~> 1.3, >= 1.3.6)
+  sqlite3 (~> 1.4)
   stackprof
   sucker_punch
   turbolinks (~> 5)

activerecord/lib/active_record/connection_adapters/sqlite3/database_statements.rb

@@ -14,7 +14,7 @@ module ActiveRecord
 
             log(sql, name) do
               ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
-                @connection.execute_batch(sql)
+                @connection.execute_batch2(sql)
               end
             end
           end

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -10,7 +10,7 @@ require "active_record/connection_adapters/sqlite3/schema_definitions"
 require "active_record/connection_adapters/sqlite3/schema_dumper"
 require "active_record/connection_adapters/sqlite3/schema_statements"
 
-gem "sqlite3", "~> 1.3", ">= 1.3.6"
+gem "sqlite3", "~> 1.4"
 require "sqlite3"
 
 module ActiveRecord

railties/lib/rails/generators/database.rb

@@ -15,7 +15,7 @@ module Rails
         case database
         when "mysql"          then ["mysql2", [">= 0.4.4"]]
         when "postgresql"     then ["pg", [">= 0.18", "< 2.0"]]
-        when "sqlite3"        then ["sqlite3", ["~> 1.3", ">= 1.3.6"]]
+        when "sqlite3"        then ["sqlite3", ["~> 1.4"]]
         when "oracle"         then ["activerecord-oracle_enhanced-adapter", nil]
         when "frontbase"      then ["ruby-frontbase", nil]
         when "sqlserver"      then ["activerecord-sqlserver-adapter", nil]

railties/test/generators/app_generator_test.rb

@@ -526,7 +526,7 @@ class AppGeneratorTest < Rails::Generators::TestCase
     if defined?(JRUBY_VERSION)
       assert_gem "activerecord-jdbcsqlite3-adapter"
     else
-      assert_gem "sqlite3", "'~> 1.3', '>= 1.3.6'"
+      assert_gem "sqlite3", "'~> 1.4'"
     end
   end
 

railties/test/generators/db_system_change_generator_test.rb

@@ -68,7 +68,7 @@ module Rails
 
             assert_file("Gemfile") do |content|
               assert_match "# Use sqlite3 as the database for Active Record", content
-              assert_match "gem 'sqlite3', '~> 1.3', '>= 1.3.6'", content
+              assert_match "gem 'sqlite3', '~> 1.4'", content
             end
           end